1. Field of the Invention
This invention relates to welding apparatus, more particularly to welding apparatus suitable for welding together large size synthetic resin molded articles having relatively large areas to be welded together.
2. Description of the Prior Art
Preparation of a product by welding together a plurality of molded articles or pieces produced by injection or extruding machines, for example, has been old and various types of welding apparatus have been used depending upon the type of the products.
Generally, the welding apparatus of the type described above includes a holding mechanism for holding the molded articles to be welded together in opposing positions, a heating mechanism for fusing or melting the surfaces of the articles to be welded together and a press mechanism for causing the molded articles to abut each other with their welding surfaces fused.
When welding together molded articles with the apparatus of the type referred to above, particularly where the articles are of a large size and have narrow widths to be welded together, for example, where the ends of plate shaped members are to be welded together, due to the difference in the warpage or shrinkage the relative positions of the molded articles are often offset thus decreasing the mechanical strength of the welded portion.